According to TIME.com, Steinhauser, professor of ecology and radiation studies at Germany's Leibniz University, published a study eight years ago all about the nature of 'navel fluff' (it's scientific name) and deduced that it was mainly a collection of threads and fibres from clothing, after he collected a whopping 503 samples from his own belly button. He also found that there could be traces of house dust, dead skin cells, fat, proteins and sweat.

Alongside the above, you might also find highly diverse bacteria in your naval fluff – none of which are particularly harmful. TIME.com also spoke to Dr Rob Danoff, a physician from in Philadelphia, who has collected fluff from patients' belly buttons to find that 'there's a little ecosystem in your navel, but it seems harmless'.

Dr Danoff adds that, unsurprisingly, the colour of the fluff usually matches what you've been wearing. 'I've had a patient come in worried because his belly button lint had turned blue, and I told him it was probably from his blue jeans,' he told the website.

People with 'outies' are less likely to accumulate naval fluff, while middle-aged, hairy men who haverecently put on weight are more likely to have belly button lint, according to the findings from the University of Sydney's Dr Karl Kruszelnicki. His research also revealed that shaving the hair from around your belly button reduced the amount of lint that collected in your naval, because the hairs operate as a 'one-way ratchet mechanism'.

No matter how tempting, don't try to dig out the fluff with a nail as you could break the skin and risk infection. Dr Danoff says you're better off waiting until the fluff builds up enough and spraying it with shower water, so you can pull it out when you're in the shower and it gets wet.

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